<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Intracellular messenger formed by the action of phospholipase C on phosphatidylinositol 4,5-bisphosphate, which is one of the phospholipids that make up the cell membrane. Inositol 1,4,5-trisphosphate is released into the cytoplasm where it releases calcium ions from internal stores within the cell's endoplasmic reticulum. These calcium ions stimulate the activity of B kinase or calmodulin.</n0:def-definition><n0:def-source>MSH2002_06_01</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A phosphatidylinositol with phosphate covalently bound in the 4 and 5 positions of the inositol group. Inositol 1,4,5-trisphosphate acts as an intermediate in the IP3/DAG pathway, hydrolyzed by phospholipase C and liberating diacylglycerol and PIP2, which activate Protein Kinase C and calcium release from the endoplasmic reticulum, respectively.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>